Installation of a GREE FLEXX R32 electric furnace in Clarenceville, Saint-Georges-de-Clarenceville (Haut-Richelieu RCM)

A complete central system in a two-by-two-meter storage room

At Clarenceville, just minutes from the Vermont border and Lake Champlain, we installed a central system GREE FLEXX R32 in what, until the morning of the project, had been a basement storage closet filled with shelves, boxes, and storage bins.

This kind of space is the reality for most homes in the rural Haut-Richelieu and Montérégie. The basement is finished, the mechanical room was never designed as such, and the equipment must coexist with the family's storage. A rushed installer sees available space. We see four distinct constraints to address before even taking the equipment out of its box: room volume, service clearances, refrigerant line routing, and condensate drainage on a finished floor.

The context: no natural gas, an existing ductwork system, and a winter bill to reduce

Saint-Georges-de-Clarenceville is not served by natural gas. As throughout this part of the Haut-Richelieu, heating is provided by electricity, propane, or oil, and homes equipped with a ductwork system almost always use an electric furnace.

The customer had exactly this setup: a well-maintained air distribution system, a return plenum with filter, and 100% resistance heating. His request came down to two points. Add air conditioning, because the humidity rising from Lake Champlain in July makes the upper floors difficult to live in. And reduce the resistive portion of his heating bill without touching the existing ductwork or renovating his basement.

This is the scenario in which the FLEXX R32 is most effective: the air handler cabinet takes the place of the old unit, the ductwork remains intact, and the electric furnace remains in place, but as backup rather than the primary system.

The installed equipment and its certified data

The selected configuration is a 4-ton GREE FLEXX R32:

• Indoor unit (air handler cabinet): GUD48AH2/G-D(U)
• Outdoor unit: GUD60W2/NhE-D(U)
• AHRI number : 217120761
• Cooling capacity: 48,000 BTU/h nominal, modulation from 34,000 to 50,000 BTU/h
• Heating capacity: 48,000 BTU/h nominal, modulation from 34,000 to 52,000 BTU/h
• TRÉS2 (SEER2): 19, the best cooling value in the entire FLEXX range
• CPSC2 (HSPF2) : 10
• TRÉ2 (EER2) : 12 — COP : 3,4
• Refrigerant: R32, factory charge of 4.6 kg
• Heating range: -30 °C to 24 °C — Cooling range: -15 °C to 54 °C
• Airflow: 1,200 CFM at a nominal external static pressure of 125 Pa (0.5 in. w.g.)
• Power supply: 208–230 V, MCA of 7.1 A and MOCP of 15 A for the indoor cabinet
• Outdoor unit: MCA of 39.9 A and MOCP of 45 A, two 1/6 HP fan motors
• Weight: 90.5 kg for the indoor unit, 109.5 kg for the outdoor unit
• ENERGY STAR certification, A2L leak-detection sensor included, factory-installed Wi-Fi module, controlled by a conventional 24 VAC thermostat

The THERMOLEC Electric Furnace: A Separate Unit Mounted in the Duct

This is where this project differs from most of the installations we document.

In the photo, the white THERMOLEC enclosure mounted on the plenum, to the left of the GREE air handler, is not a decorative accessory: it is the system’s electric furnace. Rather than using a heating kit inserted into the air handler, we retained a duct-mounted electric heater connected to the network by a section of insulated flexible duct.

Why Choose a Duct Heater Instead of an Integrated Kit

This choice is not a compromise. It offers three concrete advantages, especially in renovations:

1. Power flexibility. Integrated kits come in a limited number of capacities. A duct heater makes it possible to adjust the supplemental heating capacity to the building’s actual load calculation rather than to whatever is available in inventory.
2. Service accessibility. The elements, limiters, and contactors are housed in a standalone enclosure accessible through a single panel. In a utility room where the main air handler is wedged between two walls, this separation is worth its weight in gold during a service call in January.
3. Electrical separation. The heating circuit is independent of the air handler’s circuit, which simplifies troubleshooting and makes it possible to shut off the supplemental heat without depriving the house of ventilation.

Rules Never to Bypass for an Electric Duct Heater

A duct heater is simple, but it is uncompromising on four points—and that is where poorly executed installations reveal themselves a few years later:

• It must be downstream of the air handler, never on the return. The air passes through the fan first, then through the elements.
• It requires proof of airflow. The unit must only be able to energize its elements when the fan is actually running. The interlock is provided by the control and an airflow safety device, with a manual-reset backup thermal limit switch.
• It requires a straight length of duct upstream and downstream so that air is distributed evenly across the elements. An elbow connected directly to the outlet creates zones where air stagnates and the limit switch eventually trips.
• It requires a service clearance that remains unobstructed at all times. In a storage room, that means the box of Christmas decorations cannot go back there in January.

The control logic: two sources, one thermostat

In heating mode, the heat pump meets the demand until the outdoor temperature falls below the home's balance point. Below that point, or during defrost cycles, the THERMOLEC electric furnace takes over partially or completely.

The 24 VAC thermostat configuration determines whether the customer will actually save money. Three settings are checked during commissioning: heat pump mode with auxiliary heat (not two conventional stages), reversing valve polarity, and above all the auxiliary heat lockout. Without the latter, electric resistance heat engages every time the setpoint rises, making the seasonal efficiency rating of 10 CPSC2 merely theoretical.

The storage room: the A2L calculation that too many people skip

R32 is classified as A2L, slightly flammable. The FLEXX includes a factory-installed A2L leak detection sensor that, when a leak is detected, starts the indoor fan to disperse the refrigerant.

This safety measure relies on one assumption: the room has sufficient volume and air can circulate within it. The notice affixed to the cabinet specifies a minimum floor area based on the refrigerant charge. With 4.6 kg of R32 in this configuration, the required value is the highest in the range.

In an enclosed storage room, two checks are essential before installation, not afterward:

• The actual room volume, measured rather than estimated. If the room is too small, the solution is a transfer grille or a louvered door to the adjacent space, not an optimistic approximation.
• Freedom for air to circulate around the unit. A fan drawing air against a wall of plastic bins does not disperse anything.

We systematically leave the customer written instructions: the shelves may remain, but boxes must not be placed in front of access panels or against the grilles.

Condensate: the float switch is the least expensive insurance on the jobsite

The condensate connection visible at the bottom of the unit combines several components that we install as standard:

1. A trap sized according to the fan pressure.
2. Two red cleanout plugs, positioned so that a brush can be inserted without disassembling the piping.
3. A transparent cleanout, which allows the flow to be visually checked during the cooling season.
4. A safety float switch, whose orange wires run up to the unit controls.

This last point deserves emphasis. A 4-ton coil in the peak humidity of July, in the Lake Champlain area, produces several liters of water per day. If the drain becomes clogged, the float switch shuts down the system before the pan overflows. The customer is left with a hot house and a service call rather than a finished floor that needs to be redone. It is a component costing a few dollars that prevents the most expensive claims we see in the trade.

The refrigerant line, the filter-drier, and routing through a cluttered room

The refrigerant line enters through the top of the room, runs along the right wall, and descends toward the unit connections. The suction line is insulated along its entire length, the liquid line remains bare copper indoors, and a filter-drier is installed on the liquid line.

Three technical details about this section:

• The diameter is 3/8 in. on the liquid line and 3/4 in. on the gas line for this configuration.
• The precharge length is 7.5 m. Beyond that, the additional charge is 20 g per meter for the 48,000 and 54,000 BTU models, compared with 30 g per meter for the smaller ones. The maximum length between the units is 30 m, with a maximum elevation difference of 15 m.
• The charge is weighed on a scale and then recorded on a label affixed to the unit. A technician servicing the system eight years from now must know how much refrigerant is in it without having to guess.

In a room where metal shelving is installed 30 cm from the line, we secure and protect the routing so that a bin pushed a little too quickly does not bend a copper tube. This detail never appears in a quote. It appears in service calls.

Mistakes to avoid with this type of installation

1. Install it in an enclosed room without performing the A2L volume calculation. This is the check most often omitted on R32 systems, and it is a requirement, not a recommendation.
2. Install the electric duct heater on the return. It must be downstream of the fan, without exception.
3. Not installing a safety float switch on a unit located above a finished floor.
4. Matching the capacity of the old furnace without performing a load calculation. A 4-ton cabinet in a home that needs 2.5 tons will short-cycle and dehumidify poorly in summer.
5. Neglecting the static pressure of the existing ductwork. The cabinet delivers its rated airflow at 125 Pa; an overly dense filter or a constricted transition reduces performance without triggering any indicator light.
6. Allowing the room to fill up with storage after the technicians leave. Service clearances and airflow are useful only if they are maintained.

Eligibility for rebates

The GREE FLEXX R32 is ENERGY STAR certified, and each indoor-outdoor pair has a distinct AHRI number. Here, it is 217120761. This number—not the product line's commercial name—is what government programs and distributors require to validate eligibility for applicable rebates.

The criteria and amounts vary depending on the programs and periods. We confirm that the exact configuration is eligible before signing the contract, and we provide the corresponding AHRI certificate with the invoice. A mismatched pair on paper is enough to have a complete application rejected, even if the installation is flawless.

What we learned from the Clarenceville project

Converting an electric furnace to a central heat pump system is not simply a matter of replacing one box with another. On this project, the added value came from decisions that cost almost nothing when made at the right time: measuring the room volume before ordering, positioning the duct heater downstream with the required straight length, installing a safety float switch, protecting the line-set route in a cluttered room, and documenting the refrigerant charge on the unit.

At AirGreen, we install and maintain HVAC systems in Clarenceville, Saint-Georges-de-Clarenceville, throughout the Haut-Richelieu RCM and Montérégie, as well as in Montreal, Laval, Longueuil, on the North Shore, and on the South Shore. Our technicians measure static pressure, weigh the refrigerant charge, configure the auxiliary electric heat lockout, and provide the customer with written commissioning readings.

For an assessment of your home and a detailed quote for a GREE FLEXX R32 central system with auxiliary electric heating, contact our team. We come to your home, take measurements, and explain every decision before disconnecting anything.